if you want a faster way, try firefly, you might get a good deal. they use fokker f50 though, and you will fly into senai.
if you use airasia also same, fly to senai airport then you take the coach (buy ticket out in front) to city lounge. get off there then take yellow bus to check point, get off, do the passport thing, get back on the same bus or another yellow bus (keep your ticket stub). then at singapore side, just take yellow bus to the nearest MRT station and go from there or take taxi lor.

Very easy, i always go thru JB when i go SG but this year I don't think I will go SG anymore cos basi liaw. shopping malls, the newer ones are like vivocity lor, well you know what they say, you seen one, you seen them all!